Field of the Invention
The present invention relates to a sealing unit and a projector including this sealing unit.
Description of the Related Art
In these days, projectors are used on many occasions as image projection systems which project a screen of a personal computer and a video image, as well as images based on image data which is stored on a memory card onto a screen. These projectors are such that light emitted from a light source is collected onto a micromirror display device called a digital micromirror device (DMD) or a liquid crystal panel, so that a color image is projected onto a screen for display.
The application of these projectors as image projection systems is expanded from a presentation in a business scene to a domestic use in association with the propagation of personal computers and video equipment such as DVD players. Conventionally, the mainstream of these projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made developments of various types of projectors which use, as a light source, a plurality of semiconductor light emitting devices such as laser diodes.
For example, Japanese Unexamined Patent Application No. 2014-194501 discloses a projector for a head-up display system which utilizes as light sources laser diodes which emit lights in the red, green and blue wavelength ranges. The red, green and blue laser diodes and optical modules are accommodated in a case. A plurality of cylindrical heat conductive members are attached to opening portions in a lower surface of the case. An annular groove is formed around an outer circumference of each of the heat conductive members, so that a seal member which is an O-ring is fitted in the annular groove. Inner end faces of the heat conductive members are thermally connected to an LD holder which holds the laser diodes. Peltier devices are provided on outer end faces of the heat conductive members for thermal connection. These Peltier devices are connected to a heat dissipating plate having a number of fins.
Normally, predetermined permissible assemblage tolerances in relation to the attaching dimensions to the case are given to the members such as the LD holder and the optical modules which are provided within the case and which constitute objects to be cooled. Then, the heat conductive members which are attachment members to be attached to the case are attached to the case in such a way that the inner end faces of the heat conductive members are brought into face contact with a contact surface of the LD holder so that heat is conducted effectively. As this occurs, in case the LD holder is attached obliquely to the case within the permitted assemblage tolerance, the heat conductive members are attached obliquely to the opening portions of the case. Then, there may be caused a case where the O-rings of the heat conductive members are not pressed sufficiently to the opening portions of the case or the O-rings are twisted so as not to seal the opening portions as required in attaching the heat conductive members to the opening portions.